As Barack Obama prepares for the 'no-necktie summit' with the Chinese leader Xi Jinping in California, we decided to look at the two superpowers and compare data such as health, wealth and environmental development – an inherently tricky task given the countries' markedly different systems. Can it be done? Join the debate here

It's like a scene from the prisoner, with enormous balls of gas bouncing down Fifth Avenue. But this is a visualisation of carbon pollution in New York by The Carbon Quilt, which specalises in visualising Greenhouse Gases

Which countries in the world emit the most carbon dioxide? How fast has China overtaken the US to reach the number one position? And why does Gibraltar have such high emissions per person? Find out for yourself

Carbon emissions for public buildings are recorded every day. In fact, more than 40,000 schools, hospitals and government departments have had their energy performance mapped. See what the data says about the ones near you